<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div{
            width: 100px;
            height: 100px;
            background-color: #a9e678;
            text-align: center;
            line-height: 100px;
        }
        .d1{
            border: 2px solid black;
        }

    </style>
</head>
<body>
    <div class="d1">
        实线
    </div>
    <br>
    <div class="d2">
        虚线
    </div>
    <br>
    <div class="d3">
        点线
    </div>
    <br>
    <div class="d4">
        单独设置边框
    </div>


</body>
</html>